1. Field of the Invention
The present invention relates to an absorbent article, such as a disposable diaper, feminine care pad, adult incontinent garment, training pant, wound dressing, and the like. Specifically, the present invention relates to an absorbent article which includes a hydrophilic flow-modulating layer adapted to receive a liquid and modulate the flow of said liquid prior to the liquid being absorbed by an absorbent body.
2. Description of the Related Art
Conventional absorbent articles typically include an absorbent body comprised of cellulosic fibers such as wood pulp fluff. The absorbent body may, in addition to the wood pulp fluff, contain particles of a high absorbency material which serves to increase the absorbent capacity of the absorbent body. In addition to the absorbent bodies, conventional absorbent articles typically comprise additional layers of material located between the body of a wearer and said absorbent body. Such layers are typically designed to perform the function of separating the body of the wearer from the absorbent body, thereby reducing the skin wetness of a wearer. In order to reduce the skin wetness of a wearer, such layers are typically formed from hydrophobic fibers.
European Patent Application EP 0 165 807A published Dec. 27, 1985, describes a sanitary napkin which includes an apertured top sheet and a resilient layer underlying the top sheet. The absorbent structure can also include a wicking layer between the apertured top sheet and the resilient layer, an absorbent core underlying the resilient layer, and a moisture barrier located against the outermost side of the absorbent core. The resilient layer is described as isolating the apertured top sheet from bodily discharges which have passed through the top sheet and as serving as a reservoir for body discharges.
U.S. Pat. No. 4,798,603 issued Jan. 17, 1989, to Meyer, et al. is directed to an absorbent article having a hydrophobic transport layer. The described absorbent articles comprise an absorbent body, a top sheet layer, and a hydrophobic transport layer. The described hydrophobic transport layer is said to reduce flow back of liquids out of the absorbent body and, as a result, provides less wetness against the skin and greater comfort to a wearer.
When a hydrophobic material is placed between the body of a wearer and an absorbent body, the degree of wetness against the skin of a wearer can, as described above, be reduced. However, the presence of the hydrophobic material may impede the flow of a liquid discharged by the wearer into the absorbent body. That is, while the hydrophobic material may prevent fluid from flowing out of the absorbent body onto the skin of a wearer, it may similarly impede the flow of liquid from a wearer to the absorbent body.
In addition to absorbent articles having hydrophobic materials located between a wearer and an absorbent body, various structures are described which comprise hydrophilic wicking layers in conjunction with an absorbent body. For example, see U.S. Pat. Nos. 4,338,371 issued July 6, 1982, to Dawn, et al.; 4,259,958 issued Apr. 7, 1981, to Goodbar; U.K. Patent Application GB 2 170 108A published July 30, 1986; U.S. Pat. Nos. 4,324,247 issued Apr. 13, 1986, to Aziz; 4,041,951 issued Aug. 16, 1977, to Sanford; 3,945,386 issued Mar. 23, 1976, to Anczurowski, et al.; and 4,413,032 issued Nov. 1, 1983, to Hartmann, et al.
The wicking structures described in the referenced patents are typically formed from a hydrophilic material having a relatively high density and, accordingly, a relatively small pore size. In fact, many of the described wicking structures are formed from wood pulp fluff which has been compressed into relatively high density layers.
While compressed layers of wood pulp fluff are, as described, capable of transporting a fluid, such layers of compressed wood pulp fluff are not generally able to rapidly receive an insult of liquid. Accordingly, such wicking layers are generally located in a manner such that a liquid discharged on the absorbent article can be absorbed by an absorbent body and then wicked throughout said absorbent body. If such wicking layers comprising compressed wood pulp fluff are located between the body of a wearer and an absorbent body, liquids discharged on the absorbent article find it difficult to pass through the wicking layer into the absorbent body at speeds sufficient to prevent leakage from the absorbent articles.
Thus, conventional absorbent articles have not been completely satisfactory. Specifically, the absorbent articles have not been sufficiently able to both rapidly receive and distribute a discharged liquid, thereby modulating the flow of said liquid prior to absorption of the liquid by an absorbent body.